Mercurial > minori
diff dep/fmt/doc/html/syntax.html @ 343:1faa72660932
*: transfer back to cmake from autotools
autotools just made lots of things more complicated than
they should have and many things broke (i.e. translations)
| author | Paper <paper@paper.us.eu.org> |
|---|---|
| date | Thu, 20 Jun 2024 05:56:06 -0400 |
| parents | |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/dep/fmt/doc/html/syntax.html Thu Jun 20 05:56:06 2024 -0400 @@ -0,0 +1,828 @@ +<!DOCTYPE html> + + +<html lang="en"> + <head> + <meta charset="utf-8"> + <meta http-equiv="X-UA-Compatible" content="IE=edge"> + <meta name="viewport" content="width=device-width, initial-scale=1"> + + <meta name="generator" content="Docutils 0.17.1: http://docutils.sourceforge.net/" /> + + <title>Format String Syntax — fmt 10.2.1 documentation</title> + + <link rel="stylesheet" href="_static/basic.css" type="text/css" /> + <link rel="stylesheet" href="_static/pygments.css" type="text/css" /> + <link rel="stylesheet" href="_static/breathe.css" type="text/css" /> + + <script type="text/javascript"> + var DOCUMENTATION_OPTIONS = { + URL_ROOT: './', + VERSION: '10.2.1', + COLLAPSE_INDEX: false, + FILE_SUFFIX: '.html', + LINK_SUFFIX: '.html', + SOURCELINK_SUFFIX: '.txt', + HAS_SOURCE: true, + SOURCELINK_SUFFIX: '.txt' + }; + </script> + <script src="_static/jquery.js"></script> + <script src="_static/underscore.js"></script> + <script src="_static/doctools.js"></script> + <script src="_static/language_data.js"></script> + <link rel="index" title="Index" href="genindex.html" /> + <link rel="search" title="Search" href="search.html" /> +<meta name="description" content="Small, safe and fast formatting library"> +<meta name="keywords" content="C++, formatting, printf, string, library"> +<meta name="author" content="Victor Zverovich"> +<link rel="stylesheet" href="_static/fmt.css"> + +<script async src="https://www.googletagmanager.com/gtag/js?id=UA-20116650-4"></script> +<script> + window.dataLayer = window.dataLayer || []; + function gtag(){dataLayer.push(arguments);} + gtag('js', new Date()); + + gtag('config', 'UA-20116650-4'); +</script> + + </head> + <body role="document"> +<nav class="navbar navbar-inverse"> + <div class="tb-container"> + <div class="row"> + <div class="navbar-content"> + + <div class="navbar-header"> + <button type="button" class="navbar-toggle collapsed" + data-toggle="collapse" data-target=".navbar-collapse"> + <span class="sr-only">Toggle navigation</span> + <span class="icon-bar"></span> + <span class="icon-bar"></span> + <span class="icon-bar"></span> + </button> + <a class="navbar-brand" href="index.html">{fmt}</a> + </div> + + + <div class="collapse navbar-collapse"> + <ul class="nav navbar-nav"> + <li class="dropdown"> + <a href="#" class="dropdown-toggle" data-toggle="dropdown" + role="button" aria-expanded="false">10.2.1 + <span class="caret"></span></a> + <ul class="dropdown-menu" role="menu"> + + <li><a href="https://fmt.dev/10.2.1">10.2.1</a></li> + + <li><a href="https://fmt.dev/10.2.0">10.2.0</a></li> + + <li><a href="https://fmt.dev/10.1.1">10.1.1</a></li> + + </ul> + </li> + + + <li><a href="contents.html">Contents</a></li> + + + + <li><a href="usage.html">Usage</a></li> + + + + <li><a href="api.html">API</a></li> + + + + <li class="active"><a href="syntax.html">Syntax + <span class="sr-only">(current)</span></a></li> + + + </ul> + + +<form class="navbar-form navbar-right" role="search" action="search.html" + method="get"> + <div class="form-group"> + <input type="text" name="q" class="form-control" + placeholder="Search" > + </div> + <input type="hidden" name="check_keywords" value="yes" /> + <input type="hidden" name="area" value="default" /> + +</form> + + </div> + </div> + </div> + </div> +</nav> + + + +<div class="tb-container"> + <div class="row"> + + + <div class="content"> + + <section id="format-string-syntax"> +<span id="syntax"></span><h1>Format String Syntax<a class="headerlink" href="#format-string-syntax" title="Permalink to this headline">¶</a></h1> +<p>Formatting functions such as <a class="reference internal" href="api.html#format"><span class="std std-ref">fmt::format()</span></a> and +<a class="reference internal" href="api.html#print"><span class="std std-ref">fmt::print()</span></a> use the same format string syntax described in this +section.</p> +<p>Format strings contain “replacement fields” surrounded by curly braces <code class="docutils literal notranslate"><span class="pre">{}</span></code>. +Anything that is not contained in braces is considered literal text, which is +copied unchanged to the output. If you need to include a brace character in the +literal text, it can be escaped by doubling: <code class="docutils literal notranslate"><span class="pre">{{</span></code> and <code class="docutils literal notranslate"><span class="pre">}}</span></code>.</p> +<p>The grammar for a replacement field is as follows:</p> +<pre> +<strong id="grammar-token-sf-replacement_field"><span id="grammar-token-replacement-field"></span>replacement_field</strong> ::= "{" [<a class="reference internal" href="#grammar-token-sf-arg_id"><code class="xref docutils literal notranslate"><span class="pre">arg_id</span></code></a>] [":" (<a class="reference internal" href="#grammar-token-sf-format_spec"><code class="xref docutils literal notranslate"><span class="pre">format_spec</span></code></a> | <a class="reference internal" href="#grammar-token-sf-chrono_format_spec"><code class="xref docutils literal notranslate"><span class="pre">chrono_format_spec</span></code></a>)] "}" +<strong id="grammar-token-sf-arg_id"><span id="grammar-token-arg-id"></span>arg_id </strong> ::= <a class="reference internal" href="#grammar-token-sf-integer"><code class="xref docutils literal notranslate"><span class="pre">integer</span></code></a> | <a class="reference internal" href="#grammar-token-sf-identifier"><code class="xref docutils literal notranslate"><span class="pre">identifier</span></code></a> +<strong id="grammar-token-sf-integer"><span id="grammar-token-integer"></span>integer </strong> ::= <a class="reference internal" href="#grammar-token-sf-digit"><code class="xref docutils literal notranslate"><span class="pre">digit</span></code></a>+ +<strong id="grammar-token-sf-digit"><span id="grammar-token-digit"></span>digit </strong> ::= "0"..."9" +<strong id="grammar-token-sf-identifier"><span id="grammar-token-identifier"></span>identifier </strong> ::= <a class="reference internal" href="#grammar-token-sf-id_start"><code class="xref docutils literal notranslate"><span class="pre">id_start</span></code></a> <a class="reference internal" href="#grammar-token-sf-id_continue"><code class="xref docutils literal notranslate"><span class="pre">id_continue</span></code></a>* +<strong id="grammar-token-sf-id_start"><span id="grammar-token-id-start"></span>id_start </strong> ::= "a"..."z" | "A"..."Z" | "_" +<strong id="grammar-token-sf-id_continue"><span id="grammar-token-id-continue"></span>id_continue </strong> ::= <a class="reference internal" href="#grammar-token-sf-id_start"><code class="xref docutils literal notranslate"><span class="pre">id_start</span></code></a> | <a class="reference internal" href="#grammar-token-sf-digit"><code class="xref docutils literal notranslate"><span class="pre">digit</span></code></a> +</pre> +<p>In less formal terms, the replacement field can start with an <em>arg_id</em> +that specifies the argument whose value is to be formatted and inserted into +the output instead of the replacement field. +The <em>arg_id</em> is optionally followed by a <em>format_spec</em>, which is preceded by a +colon <code class="docutils literal notranslate"><span class="pre">':'</span></code>. These specify a non-default format for the replacement value.</p> +<p>See also the <a class="reference internal" href="#formatspec"><span class="std std-ref">Format Specification Mini-Language</span></a> section.</p> +<p>If the numerical arg_ids in a format string are 0, 1, 2, … in sequence, +they can all be omitted (not just some) and the numbers 0, 1, 2, … will be +automatically inserted in that order.</p> +<p>Named arguments can be referred to by their names or indices.</p> +<p>Some simple format string examples:</p> +<div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="s">"First, thou shalt count to {0}"</span><span class="w"> </span><span class="c1">// References the first argument</span> +<span class="s">"Bring me a {}"</span><span class="w"> </span><span class="c1">// Implicitly references the first argument</span> +<span class="s">"From {} to {}"</span><span class="w"> </span><span class="c1">// Same as "From {0} to {1}"</span> +</pre></div> +</div> +<p>The <em>format_spec</em> field contains a specification of how the value should be +presented, including such details as field width, alignment, padding, decimal +precision and so on. Each value type can define its own “formatting +mini-language” or interpretation of the <em>format_spec</em>.</p> +<p>Most built-in types support a common formatting mini-language, which is +described in the next section.</p> +<p>A <em>format_spec</em> field can also include nested replacement fields in certain +positions within it. These nested replacement fields can contain only an +argument id; format specifications are not allowed. This allows the formatting +of a value to be dynamically specified.</p> +<p>See the <a class="reference internal" href="#formatexamples"><span class="std std-ref">Format Examples</span></a> section for some examples.</p> +<section id="format-specification-mini-language"> +<span id="formatspec"></span><h2>Format Specification Mini-Language<a class="headerlink" href="#format-specification-mini-language" title="Permalink to this headline">¶</a></h2> +<p>“Format specifications” are used within replacement fields contained within a +format string to define how individual values are presented (see +<a class="reference internal" href="#syntax"><span class="std std-ref">Format String Syntax</span></a>). Each formattable type may define how the format +specification is to be interpreted.</p> +<p>Most built-in types implement the following options for format specifications, +although some of the formatting options are only supported by the numeric types.</p> +<p>The general form of a <em>standard format specifier</em> is:</p> +<pre> +<strong id="grammar-token-sf-format_spec"><span id="grammar-token-format-spec"></span>format_spec</strong> ::= [[<a class="reference internal" href="#grammar-token-sf-fill"><code class="xref docutils literal notranslate"><span class="pre">fill</span></code></a>]<a class="reference internal" href="#grammar-token-sf-align"><code class="xref docutils literal notranslate"><span class="pre">align</span></code></a>][<a class="reference internal" href="#grammar-token-sf-sign"><code class="xref docutils literal notranslate"><span class="pre">sign</span></code></a>]["#"]["0"][<a class="reference internal" href="#grammar-token-sf-width"><code class="xref docutils literal notranslate"><span class="pre">width</span></code></a>]["." <a class="reference internal" href="#grammar-token-sf-precision"><code class="xref docutils literal notranslate"><span class="pre">precision</span></code></a>]["L"][<a class="reference internal" href="#grammar-token-sf-type"><code class="xref docutils literal notranslate"><span class="pre">type</span></code></a>] +<strong id="grammar-token-sf-fill"><span id="grammar-token-fill"></span>fill </strong> ::= <a character other than '{' or '}'> +<strong id="grammar-token-sf-align"><span id="grammar-token-align"></span>align </strong> ::= "<" | ">" | "^" +<strong id="grammar-token-sf-sign"><span id="grammar-token-sign"></span>sign </strong> ::= "+" | "-" | " " +<strong id="grammar-token-sf-width"><span id="grammar-token-width"></span>width </strong> ::= <a class="reference internal" href="#grammar-token-sf-integer"><code class="xref docutils literal notranslate"><span class="pre">integer</span></code></a> | "{" [<a class="reference internal" href="#grammar-token-sf-arg_id"><code class="xref docutils literal notranslate"><span class="pre">arg_id</span></code></a>] "}" +<strong id="grammar-token-sf-precision"><span id="grammar-token-precision"></span>precision </strong> ::= <a class="reference internal" href="#grammar-token-sf-integer"><code class="xref docutils literal notranslate"><span class="pre">integer</span></code></a> | "{" [<a class="reference internal" href="#grammar-token-sf-arg_id"><code class="xref docutils literal notranslate"><span class="pre">arg_id</span></code></a>] "}" +<strong id="grammar-token-sf-type"><span id="grammar-token-type"></span>type </strong> ::= "a" | "A" | "b" | "B" | "c" | "d" | "e" | "E" | "f" | "F" | "g" | "G" | + "o" | "p" | "s" | "x" | "X" | "?" +</pre> +<p>The <em>fill</em> character can be any Unicode code point other than <code class="docutils literal notranslate"><span class="pre">'{'</span></code> or +<code class="docutils literal notranslate"><span class="pre">'}'</span></code>. The presence of a fill character is signaled by the character following +it, which must be one of the alignment options. If the second character of +<em>format_spec</em> is not a valid alignment option, then it is assumed that both the +fill character and the alignment option are absent.</p> +<p>The meaning of the various alignment options is as follows:</p> +<table class="docutils align-default"> +<colgroup> +<col style="width: 13%" /> +<col style="width: 87%" /> +</colgroup> +<thead> +<tr class="row-odd"><th class="head"><p>Option</p></th> +<th class="head"><p>Meaning</p></th> +</tr> +</thead> +<tbody> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'<'</span></code></p></td> +<td><p>Forces the field to be left-aligned within the available +space (this is the default for most objects).</p></td> +</tr> +<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'>'</span></code></p></td> +<td><p>Forces the field to be right-aligned within the +available space (this is the default for numbers).</p></td> +</tr> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'^'</span></code></p></td> +<td><p>Forces the field to be centered within the available +space.</p></td> +</tr> +</tbody> +</table> +<p>Note that unless a minimum field width is defined, the field width will always +be the same size as the data to fill it, so that the alignment option has no +meaning in this case.</p> +<p>The <em>sign</em> option is only valid for floating point and signed integer types, +and can be one of the following:</p> +<table class="docutils align-default"> +<colgroup> +<col style="width: 13%" /> +<col style="width: 87%" /> +</colgroup> +<thead> +<tr class="row-odd"><th class="head"><p>Option</p></th> +<th class="head"><p>Meaning</p></th> +</tr> +</thead> +<tbody> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'+'</span></code></p></td> +<td><p>indicates that a sign should be used for both +nonnegative as well as negative numbers.</p></td> +</tr> +<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'-'</span></code></p></td> +<td><p>indicates that a sign should be used only for negative +numbers (this is the default behavior).</p></td> +</tr> +<tr class="row-even"><td><p>space</p></td> +<td><p>indicates that a leading space should be used on +nonnegative numbers, and a minus sign on negative numbers.</p></td> +</tr> +</tbody> +</table> +<p>The <code class="docutils literal notranslate"><span class="pre">'#'</span></code> option causes the “alternate form” to be used for the +conversion. The alternate form is defined differently for different +types. This option is only valid for integer and floating-point types. +For integers, when binary, octal, or hexadecimal output is used, this +option adds the prefix respective <code class="docutils literal notranslate"><span class="pre">"0b"</span></code> (<code class="docutils literal notranslate"><span class="pre">"0B"</span></code>), <code class="docutils literal notranslate"><span class="pre">"0"</span></code>, or +<code class="docutils literal notranslate"><span class="pre">"0x"</span></code> (<code class="docutils literal notranslate"><span class="pre">"0X"</span></code>) to the output value. Whether the prefix is +lower-case or upper-case is determined by the case of the type +specifier, for example, the prefix <code class="docutils literal notranslate"><span class="pre">"0x"</span></code> is used for the type <code class="docutils literal notranslate"><span class="pre">'x'</span></code> +and <code class="docutils literal notranslate"><span class="pre">"0X"</span></code> is used for <code class="docutils literal notranslate"><span class="pre">'X'</span></code>. For floating-point numbers the +alternate form causes the result of the conversion to always contain a +decimal-point character, even if no digits follow it. Normally, a +decimal-point character appears in the result of these conversions +only if a digit follows it. In addition, for <code class="docutils literal notranslate"><span class="pre">'g'</span></code> and <code class="docutils literal notranslate"><span class="pre">'G'</span></code> +conversions, trailing zeros are not removed from the result.</p> +<p><em>width</em> is a decimal integer defining the minimum field width. If not +specified, then the field width will be determined by the content.</p> +<p>Preceding the <em>width</em> field by a zero (<code class="docutils literal notranslate"><span class="pre">'0'</span></code>) character enables sign-aware +zero-padding for numeric types. It forces the padding to be placed after the +sign or base (if any) but before the digits. This is used for printing fields in +the form ‘+000000120’. This option is only valid for numeric types and it has no +effect on formatting of infinity and NaN.</p> +<p>The <em>precision</em> is a decimal number indicating how many digits should be +displayed after the decimal point for a floating-point value formatted with +<code class="docutils literal notranslate"><span class="pre">'f'</span></code> and <code class="docutils literal notranslate"><span class="pre">'F'</span></code>, or before and after the decimal point for a floating-point +value formatted with <code class="docutils literal notranslate"><span class="pre">'g'</span></code> or <code class="docutils literal notranslate"><span class="pre">'G'</span></code>. For non-number types the field +indicates the maximum field size - in other words, how many characters will be +used from the field content. The <em>precision</em> is not allowed for integer, +character, Boolean, and pointer values. Note that a C string must be +null-terminated even if precision is specified.</p> +<p>The <code class="docutils literal notranslate"><span class="pre">'L'</span></code> option uses the current locale setting to insert the appropriate +number separator characters. This option is only valid for numeric types.</p> +<p>Finally, the <em>type</em> determines how the data should be presented.</p> +<p>The available string presentation types are:</p> +<table class="docutils align-default"> +<colgroup> +<col style="width: 13%" /> +<col style="width: 87%" /> +</colgroup> +<thead> +<tr class="row-odd"><th class="head"><p>Type</p></th> +<th class="head"><p>Meaning</p></th> +</tr> +</thead> +<tbody> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'s'</span></code></p></td> +<td><p>String format. This is the default type for strings and +may be omitted.</p></td> +</tr> +<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'?'</span></code></p></td> +<td><p>Debug format. The string is quoted and special +characters escaped.</p></td> +</tr> +<tr class="row-even"><td><p>none</p></td> +<td><p>The same as <code class="docutils literal notranslate"><span class="pre">'s'</span></code>.</p></td> +</tr> +</tbody> +</table> +<p>The available character presentation types are:</p> +<table class="docutils align-default"> +<colgroup> +<col style="width: 13%" /> +<col style="width: 87%" /> +</colgroup> +<thead> +<tr class="row-odd"><th class="head"><p>Type</p></th> +<th class="head"><p>Meaning</p></th> +</tr> +</thead> +<tbody> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'c'</span></code></p></td> +<td><p>Character format. This is the default type for +characters and may be omitted.</p></td> +</tr> +<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'?'</span></code></p></td> +<td><p>Debug format. The character is quoted and special +characters escaped.</p></td> +</tr> +<tr class="row-even"><td><p>none</p></td> +<td><p>The same as <code class="docutils literal notranslate"><span class="pre">'c'</span></code>.</p></td> +</tr> +</tbody> +</table> +<p>The available integer presentation types are:</p> +<table class="docutils align-default"> +<colgroup> +<col style="width: 13%" /> +<col style="width: 87%" /> +</colgroup> +<thead> +<tr class="row-odd"><th class="head"><p>Type</p></th> +<th class="head"><p>Meaning</p></th> +</tr> +</thead> +<tbody> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'b'</span></code></p></td> +<td><p>Binary format. Outputs the number in base 2. Using the +<code class="docutils literal notranslate"><span class="pre">'#'</span></code> option with this type adds the prefix <code class="docutils literal notranslate"><span class="pre">"0b"</span></code> +to the output value.</p></td> +</tr> +<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'B'</span></code></p></td> +<td><p>Binary format. Outputs the number in base 2. Using the +<code class="docutils literal notranslate"><span class="pre">'#'</span></code> option with this type adds the prefix <code class="docutils literal notranslate"><span class="pre">"0B"</span></code> +to the output value.</p></td> +</tr> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'c'</span></code></p></td> +<td><p>Character format. Outputs the number as a character.</p></td> +</tr> +<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'d'</span></code></p></td> +<td><p>Decimal integer. Outputs the number in base 10.</p></td> +</tr> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'o'</span></code></p></td> +<td><p>Octal format. Outputs the number in base 8.</p></td> +</tr> +<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'x'</span></code></p></td> +<td><p>Hex format. Outputs the number in base 16, using +lower-case letters for the digits above 9. Using the +<code class="docutils literal notranslate"><span class="pre">'#'</span></code> option with this type adds the prefix <code class="docutils literal notranslate"><span class="pre">"0x"</span></code> +to the output value.</p></td> +</tr> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'X'</span></code></p></td> +<td><p>Hex format. Outputs the number in base 16, using +upper-case letters for the digits above 9. Using the +<code class="docutils literal notranslate"><span class="pre">'#'</span></code> option with this type adds the prefix <code class="docutils literal notranslate"><span class="pre">"0X"</span></code> +to the output value.</p></td> +</tr> +<tr class="row-odd"><td><p>none</p></td> +<td><p>The same as <code class="docutils literal notranslate"><span class="pre">'d'</span></code>.</p></td> +</tr> +</tbody> +</table> +<p>Integer presentation types can also be used with character and Boolean values +with the only exception that <code class="docutils literal notranslate"><span class="pre">'c'</span></code> cannot be used with <code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">bool</span></code>. Boolean values +are formatted using textual representation, either <code class="docutils literal notranslate"><span class="pre">true</span></code> or <code class="docutils literal notranslate"><span class="pre">false</span></code>, if the +presentation type is not specified.</p> +<p>The available presentation types for floating-point values are:</p> +<table class="docutils align-default"> +<colgroup> +<col style="width: 13%" /> +<col style="width: 87%" /> +</colgroup> +<thead> +<tr class="row-odd"><th class="head"><p>Type</p></th> +<th class="head"><p>Meaning</p></th> +</tr> +</thead> +<tbody> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'a'</span></code></p></td> +<td><p>Hexadecimal floating point format. Prints the number in +base 16 with prefix <code class="docutils literal notranslate"><span class="pre">"0x"</span></code> and lower-case letters for +digits above 9. Uses <code class="docutils literal notranslate"><span class="pre">'p'</span></code> to indicate the exponent.</p></td> +</tr> +<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'A'</span></code></p></td> +<td><p>Same as <code class="docutils literal notranslate"><span class="pre">'a'</span></code> except it uses upper-case letters for +the prefix, digits above 9 and to indicate the exponent.</p></td> +</tr> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'e'</span></code></p></td> +<td><p>Exponent notation. Prints the number in scientific +notation using the letter ‘e’ to indicate the exponent.</p></td> +</tr> +<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'E'</span></code></p></td> +<td><p>Exponent notation. Same as <code class="docutils literal notranslate"><span class="pre">'e'</span></code> except it uses an +upper-case <code class="docutils literal notranslate"><span class="pre">'E'</span></code> as the separator character.</p></td> +</tr> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'f'</span></code></p></td> +<td><p>Fixed point. Displays the number as a fixed-point +number.</p></td> +</tr> +<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'F'</span></code></p></td> +<td><p>Fixed point. Same as <code class="docutils literal notranslate"><span class="pre">'f'</span></code>, but converts <code class="docutils literal notranslate"><span class="pre">nan</span></code> to +<code class="docutils literal notranslate"><span class="pre">NAN</span></code> and <code class="docutils literal notranslate"><span class="pre">inf</span></code> to <code class="docutils literal notranslate"><span class="pre">INF</span></code>.</p></td> +</tr> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'g'</span></code></p></td> +<td><p>General format. For a given precision <code class="docutils literal notranslate"><span class="pre">p</span> <span class="pre">>=</span> <span class="pre">1</span></code>, +this rounds the number to <code class="docutils literal notranslate"><span class="pre">p</span></code> significant digits and +then formats the result in either fixed-point format +or in scientific notation, depending on its magnitude.</p> +<p>A precision of <code class="docutils literal notranslate"><span class="pre">0</span></code> is treated as equivalent to a +precision of <code class="docutils literal notranslate"><span class="pre">1</span></code>.</p> +</td> +</tr> +<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'G'</span></code></p></td> +<td><p>General format. Same as <code class="docutils literal notranslate"><span class="pre">'g'</span></code> except switches to +<code class="docutils literal notranslate"><span class="pre">'E'</span></code> if the number gets too large. The +representations of infinity and NaN are uppercased, too.</p></td> +</tr> +<tr class="row-even"><td><p>none</p></td> +<td><p>Similar to <code class="docutils literal notranslate"><span class="pre">'g'</span></code>, except that the default precision is +as high as needed to represent the particular value.</p></td> +</tr> +</tbody> +</table> +<p>The available presentation types for pointers are:</p> +<table class="docutils align-default"> +<colgroup> +<col style="width: 13%" /> +<col style="width: 87%" /> +</colgroup> +<thead> +<tr class="row-odd"><th class="head"><p>Type</p></th> +<th class="head"><p>Meaning</p></th> +</tr> +</thead> +<tbody> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'p'</span></code></p></td> +<td><p>Pointer format. This is the default type for +pointers and may be omitted.</p></td> +</tr> +<tr class="row-odd"><td><p>none</p></td> +<td><p>The same as <code class="docutils literal notranslate"><span class="pre">'p'</span></code>.</p></td> +</tr> +</tbody> +</table> +</section> +<section id="chrono-format-specifications"> +<span id="chrono-specs"></span><h2>Chrono Format Specifications<a class="headerlink" href="#chrono-format-specifications" title="Permalink to this headline">¶</a></h2> +<p>Format specifications for chrono duration and time point types as well as +<code class="docutils literal notranslate"><span class="pre">std::tm</span></code> have the following syntax:</p> +<pre> +<strong id="grammar-token-sf-chrono_format_spec"><span id="grammar-token-chrono-format-spec"></span>chrono_format_spec</strong> ::= [[<a class="reference internal" href="#grammar-token-sf-fill"><code class="xref docutils literal notranslate"><span class="pre">fill</span></code></a>]<a class="reference internal" href="#grammar-token-sf-align"><code class="xref docutils literal notranslate"><span class="pre">align</span></code></a>][<a class="reference internal" href="#grammar-token-sf-width"><code class="xref docutils literal notranslate"><span class="pre">width</span></code></a>]["." <a class="reference internal" href="#grammar-token-sf-precision"><code class="xref docutils literal notranslate"><span class="pre">precision</span></code></a>][<a class="reference internal" href="#grammar-token-sf-chrono_specs"><code class="xref docutils literal notranslate"><span class="pre">chrono_specs</span></code></a>] +<strong id="grammar-token-sf-chrono_specs"><span id="grammar-token-chrono-specs"></span>chrono_specs </strong> ::= [<a class="reference internal" href="#grammar-token-sf-chrono_specs"><code class="xref docutils literal notranslate"><span class="pre">chrono_specs</span></code></a>] <a class="reference internal" href="#grammar-token-sf-conversion_spec"><code class="xref docutils literal notranslate"><span class="pre">conversion_spec</span></code></a> | <a class="reference internal" href="#grammar-token-sf-chrono_specs"><code class="xref docutils literal notranslate"><span class="pre">chrono_specs</span></code></a> <a class="reference internal" href="#grammar-token-sf-literal_char"><code class="xref docutils literal notranslate"><span class="pre">literal_char</span></code></a> +<strong id="grammar-token-sf-conversion_spec"><span id="grammar-token-conversion-spec"></span>conversion_spec </strong> ::= "%" [<a class="reference internal" href="#grammar-token-sf-modifier"><code class="xref docutils literal notranslate"><span class="pre">modifier</span></code></a>] <a class="reference internal" href="#grammar-token-sf-chrono_type"><code class="xref docutils literal notranslate"><span class="pre">chrono_type</span></code></a> +<strong id="grammar-token-sf-literal_char"><span id="grammar-token-literal-char"></span>literal_char </strong> ::= <a character other than '{', '}' or '%'> +<strong id="grammar-token-sf-modifier"><span id="grammar-token-modifier"></span>modifier </strong> ::= "E" | "O" +<strong id="grammar-token-sf-chrono_type"><span id="grammar-token-chrono-type"></span>chrono_type </strong> ::= "a" | "A" | "b" | "B" | "c" | "C" | "d" | "D" | "e" | "F" | + "g" | "G" | "h" | "H" | "I" | "j" | "m" | "M" | "n" | "p" | + "q" | "Q" | "r" | "R" | "S" | "t" | "T" | "u" | "U" | "V" | + "w" | "W" | "x" | "X" | "y" | "Y" | "z" | "Z" | "%" +</pre> +<p>Literal chars are copied unchanged to the output. Precision is valid only for +<code class="docutils literal notranslate"><span class="pre">std::chrono::duration</span></code> types with a floating-point representation type.</p> +<p>The available presentation types (<em>chrono_type</em>) are:</p> +<table class="docutils align-default"> +<colgroup> +<col style="width: 12%" /> +<col style="width: 88%" /> +</colgroup> +<thead> +<tr class="row-odd"><th class="head"><p>Type</p></th> +<th class="head"><p>Meaning</p></th> +</tr> +</thead> +<tbody> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'a'</span></code></p></td> +<td><p>The abbreviated weekday name, e.g. “Sat”. If the value does not +contain a valid weekday, an exception of type <code class="docutils literal notranslate"><span class="pre">format_error</span></code> is +thrown.</p></td> +</tr> +<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'A'</span></code></p></td> +<td><p>The full weekday name, e.g. “Saturday”. If the value does not +contain a valid weekday, an exception of type <code class="docutils literal notranslate"><span class="pre">format_error</span></code> is +thrown.</p></td> +</tr> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'b'</span></code></p></td> +<td><p>The abbreviated month name, e.g. “Nov”. If the value does not +contain a valid month, an exception of type <code class="docutils literal notranslate"><span class="pre">format_error</span></code> is +thrown.</p></td> +</tr> +<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'B'</span></code></p></td> +<td><p>The full month name, e.g. “November”. If the value does not +contain a valid month, an exception of type <code class="docutils literal notranslate"><span class="pre">format_error</span></code> is +thrown.</p></td> +</tr> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'c'</span></code></p></td> +<td><p>The date and time representation, e.g. “Sat Nov 12 22:04:00 1955”. +The modified command <code class="docutils literal notranslate"><span class="pre">%Ec</span></code> produces the locale’s alternate date +and time representation.</p></td> +</tr> +<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'C'</span></code></p></td> +<td><p>The year divided by 100 using floored division, e.g. “55”. If the +result is a single decimal digit, it is prefixed with 0. +The modified command <code class="docutils literal notranslate"><span class="pre">%EC</span></code> produces the locale’s alternative +representation of the century.</p></td> +</tr> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'d'</span></code></p></td> +<td><p>The day of month as a decimal number. If the result is a single +decimal digit, it is prefixed with 0. The modified command <code class="docutils literal notranslate"><span class="pre">%Od</span></code> +produces the locale’s alternative representation.</p></td> +</tr> +<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'D'</span></code></p></td> +<td><p>Equivalent to <code class="docutils literal notranslate"><span class="pre">%m/%d/%y</span></code>, e.g. “11/12/55”.</p></td> +</tr> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'e'</span></code></p></td> +<td><p>The day of month as a decimal number. If the result is a single +decimal digit, it is prefixed with a space. The modified command +<code class="docutils literal notranslate"><span class="pre">%Oe</span></code> produces the locale’s alternative representation.</p></td> +</tr> +<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'F'</span></code></p></td> +<td><p>Equivalent to <code class="docutils literal notranslate"><span class="pre">%Y-%m-%d</span></code>, e.g. “1955-11-12”.</p></td> +</tr> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'g'</span></code></p></td> +<td><p>The last two decimal digits of the ISO week-based year. If the +result is a single digit it is prefixed by 0.</p></td> +</tr> +<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'G'</span></code></p></td> +<td><p>The ISO week-based year as a decimal number. If the result is less +than four digits it is left-padded with 0 to four digits.</p></td> +</tr> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'h'</span></code></p></td> +<td><p>Equivalent to <code class="docutils literal notranslate"><span class="pre">%b</span></code>, e.g. “Nov”.</p></td> +</tr> +<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'H'</span></code></p></td> +<td><p>The hour (24-hour clock) as a decimal number. If the result is a +single digit, it is prefixed with 0. The modified command <code class="docutils literal notranslate"><span class="pre">%OH</span></code> +produces the locale’s alternative representation.</p></td> +</tr> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'I'</span></code></p></td> +<td><p>The hour (12-hour clock) as a decimal number. If the result is a +single digit, it is prefixed with 0. The modified command <code class="docutils literal notranslate"><span class="pre">%OI</span></code> +produces the locale’s alternative representation.</p></td> +</tr> +<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'j'</span></code></p></td> +<td><p>If the type being formatted is a specialization of duration, the +decimal number of days without padding. Otherwise, the day of the +year as a decimal number. Jan 1 is 001. If the result is less than +three digits, it is left-padded with 0 to three digits.</p></td> +</tr> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'m'</span></code></p></td> +<td><p>The month as a decimal number. Jan is 01. If the result is a +single digit, it is prefixed with 0. The modified command <code class="docutils literal notranslate"><span class="pre">%Om</span></code> +produces the locale’s alternative representation.</p></td> +</tr> +<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'M'</span></code></p></td> +<td><p>The minute as a decimal number. If the result is a single digit, +it is prefixed with 0. The modified command <code class="docutils literal notranslate"><span class="pre">%OM</span></code> produces the +locale’s alternative representation.</p></td> +</tr> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'n'</span></code></p></td> +<td><p>A new-line character.</p></td> +</tr> +<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'p'</span></code></p></td> +<td><p>The AM/PM designations associated with a 12-hour clock.</p></td> +</tr> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'q'</span></code></p></td> +<td><p>The duration’s unit suffix.</p></td> +</tr> +<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'Q'</span></code></p></td> +<td><p>The duration’s numeric value (as if extracted via <code class="docutils literal notranslate"><span class="pre">.count()</span></code>).</p></td> +</tr> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'r'</span></code></p></td> +<td><p>The 12-hour clock time, e.g. “10:04:00 PM”.</p></td> +</tr> +<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'R'</span></code></p></td> +<td><p>Equivalent to <code class="docutils literal notranslate"><span class="pre">%H:%M</span></code>, e.g. “22:04”.</p></td> +</tr> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'S'</span></code></p></td> +<td><p>Seconds as a decimal number. If the number of seconds is less than +10, the result is prefixed with 0. If the precision of the input +cannot be exactly represented with seconds, then the format is a +decimal floating-point number with a fixed format and a precision +matching that of the precision of the input (or to a microseconds +precision if the conversion to floating-point decimal seconds +cannot be made within 18 fractional digits). The character for the +decimal point is localized according to the locale. The modified +command <code class="docutils literal notranslate"><span class="pre">%OS</span></code> produces the locale’s alternative representation.</p></td> +</tr> +<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'t'</span></code></p></td> +<td><p>A horizontal-tab character.</p></td> +</tr> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'T'</span></code></p></td> +<td><p>Equivalent to <code class="docutils literal notranslate"><span class="pre">%H:%M:%S</span></code>.</p></td> +</tr> +<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'u'</span></code></p></td> +<td><p>The ISO weekday as a decimal number (1-7), where Monday is 1. The +modified command <code class="docutils literal notranslate"><span class="pre">%Ou</span></code> produces the locale’s alternative +representation.</p></td> +</tr> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'U'</span></code></p></td> +<td><p>The week number of the year as a decimal number. The first Sunday +of the year is the first day of week 01. Days of the same year +prior to that are in week 00. If the result is a single digit, it +is prefixed with 0. The modified command <code class="docutils literal notranslate"><span class="pre">%OU</span></code> produces the +locale’s alternative representation.</p></td> +</tr> +<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'V'</span></code></p></td> +<td><p>The ISO week-based week number as a decimal number. If the result +is a single digit, it is prefixed with 0. The modified command +<code class="docutils literal notranslate"><span class="pre">%OV</span></code> produces the locale’s alternative representation.</p></td> +</tr> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'w'</span></code></p></td> +<td><p>The weekday as a decimal number (0-6), where Sunday is 0. +The modified command <code class="docutils literal notranslate"><span class="pre">%Ow</span></code> produces the locale’s alternative +representation.</p></td> +</tr> +<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'W'</span></code></p></td> +<td><p>The week number of the year as a decimal number. The first Monday +of the year is the first day of week 01. Days of the same year +prior to that are in week 00. If the result is a single digit, it +is prefixed with 0. The modified command <code class="docutils literal notranslate"><span class="pre">%OW</span></code> produces the +locale’s alternative representation.</p></td> +</tr> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'x'</span></code></p></td> +<td><p>The date representation, e.g. “11/12/55”. The modified command +<code class="docutils literal notranslate"><span class="pre">%Ex</span></code> produces the locale’s alternate date representation.</p></td> +</tr> +<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'X'</span></code></p></td> +<td><p>The time representation, e.g. “10:04:00”. The modified command +<code class="docutils literal notranslate"><span class="pre">%EX</span></code> produces the locale’s alternate time representation.</p></td> +</tr> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'y'</span></code></p></td> +<td><p>The last two decimal digits of the year. If the result is a single +digit it is prefixed by 0. The modified command <code class="docutils literal notranslate"><span class="pre">%Oy</span></code> produces +the locale’s alternative representation. The modified command +<code class="docutils literal notranslate"><span class="pre">%Ey</span></code> produces the locale’s alternative representation of offset +from <code class="docutils literal notranslate"><span class="pre">%EC</span></code> (year only).</p></td> +</tr> +<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'Y'</span></code></p></td> +<td><p>The year as a decimal number. If the result is less than four +digits it is left-padded with 0 to four digits. The modified +command <code class="docutils literal notranslate"><span class="pre">%EY</span></code> produces the locale’s alternative full year +representation.</p></td> +</tr> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'z'</span></code></p></td> +<td><p>The offset from UTC in the ISO 8601:2004 format. For example -0430 +refers to 4 hours 30 minutes behind UTC. If the offset is zero, ++0000 is used. The modified commands <code class="docutils literal notranslate"><span class="pre">%Ez</span></code> and <code class="docutils literal notranslate"><span class="pre">%Oz</span></code> insert a +<code class="docutils literal notranslate"><span class="pre">:</span></code> between the hours and minutes: -04:30. If the offset +information is not available, an exception of type +<code class="docutils literal notranslate"><span class="pre">format_error</span></code> is thrown.</p></td> +</tr> +<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'Z'</span></code></p></td> +<td><p>The time zone abbreviation. If the time zone abbreviation is not +available, an exception of type <code class="docutils literal notranslate"><span class="pre">format_error</span></code> is thrown.</p></td> +</tr> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'%'</span></code></p></td> +<td><p>A % character.</p></td> +</tr> +</tbody> +</table> +<p>Specifiers that have a calendaric component such as <code class="docutils literal notranslate"><span class="pre">'d'</span></code> (the day of month) +are valid only for <code class="docutils literal notranslate"><span class="pre">std::tm</span></code> and time points but not durations.</p> +</section> +<section id="range-format-specifications"> +<h2>Range Format Specifications<a class="headerlink" href="#range-format-specifications" title="Permalink to this headline">¶</a></h2> +<p>Format specifications for range types have the following syntax:</p> +<pre> +<strong id="grammar-token-sf-range_format_spec"><span id="grammar-token-range-format-spec"></span>range_format_spec</strong> ::= [":" [<code class="xref docutils literal notranslate"><span class="pre">underlying_spec</span></code>]] +</pre> +<p>The <code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">underlying_spec</span></code> is parsed based on the formatter of the range’s +reference type.</p> +<p>By default, a range of characters or strings is printed escaped and quoted. But +if any <code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">underlying_spec</span></code> is provided (even if it is empty), then the characters +or strings are printed according to the provided specification.</p> +<p>Examples:</p> +<div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">fmt</span><span class="o">::</span><span class="n">format</span><span class="p">(</span><span class="s">"{}"</span><span class="p">,</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="p">{</span><span class="mi">10</span><span class="p">,</span><span class="w"> </span><span class="mi">20</span><span class="p">,</span><span class="w"> </span><span class="mi">30</span><span class="p">});</span> +<span class="c1">// Result: [10, 20, 30]</span> +<span class="n">fmt</span><span class="o">::</span><span class="n">format</span><span class="p">(</span><span class="s">"{::#x}"</span><span class="p">,</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="p">{</span><span class="mi">10</span><span class="p">,</span><span class="w"> </span><span class="mi">20</span><span class="p">,</span><span class="w"> </span><span class="mi">30</span><span class="p">});</span> +<span class="c1">// Result: [0xa, 0x14, 0x1e]</span> +<span class="n">fmt</span><span class="o">::</span><span class="n">format</span><span class="p">(</span><span class="s">"{}"</span><span class="p">,</span><span class="w"> </span><span class="n">vector</span><span class="p">{</span><span class="sc">'h'</span><span class="p">,</span><span class="w"> </span><span class="sc">'e'</span><span class="p">,</span><span class="w"> </span><span class="sc">'l'</span><span class="p">,</span><span class="w"> </span><span class="sc">'l'</span><span class="p">,</span><span class="w"> </span><span class="sc">'o'</span><span class="p">});</span> +<span class="c1">// Result: ['h', 'e', 'l', 'l', 'o']</span> +<span class="n">fmt</span><span class="o">::</span><span class="n">format</span><span class="p">(</span><span class="s">"{::}"</span><span class="p">,</span><span class="w"> </span><span class="n">vector</span><span class="p">{</span><span class="sc">'h'</span><span class="p">,</span><span class="w"> </span><span class="sc">'e'</span><span class="p">,</span><span class="w"> </span><span class="sc">'l'</span><span class="p">,</span><span class="w"> </span><span class="sc">'l'</span><span class="p">,</span><span class="w"> </span><span class="sc">'o'</span><span class="p">});</span> +<span class="c1">// Result: [h, e, l, l, o]</span> +<span class="n">fmt</span><span class="o">::</span><span class="n">format</span><span class="p">(</span><span class="s">"{::d}"</span><span class="p">,</span><span class="w"> </span><span class="n">vector</span><span class="p">{</span><span class="sc">'h'</span><span class="p">,</span><span class="w"> </span><span class="sc">'e'</span><span class="p">,</span><span class="w"> </span><span class="sc">'l'</span><span class="p">,</span><span class="w"> </span><span class="sc">'l'</span><span class="p">,</span><span class="w"> </span><span class="sc">'o'</span><span class="p">});</span> +<span class="c1">// Result: [104, 101, 108, 108, 111]</span> +</pre></div> +</div> +</section> +<section id="format-examples"> +<span id="formatexamples"></span><h2>Format Examples<a class="headerlink" href="#format-examples" title="Permalink to this headline">¶</a></h2> +<p>This section contains examples of the format syntax and comparison with +the printf formatting.</p> +<p>In most of the cases the syntax is similar to the printf formatting, with the +addition of the <code class="docutils literal notranslate"><span class="pre">{}</span></code> and with <code class="docutils literal notranslate"><span class="pre">:</span></code> used instead of <code class="docutils literal notranslate"><span class="pre">%</span></code>. +For example, <code class="docutils literal notranslate"><span class="pre">"%03.2f"</span></code> can be translated to <code class="docutils literal notranslate"><span class="pre">"{:03.2f}"</span></code>.</p> +<p>The new format syntax also supports new and different options, shown in the +following examples.</p> +<p>Accessing arguments by position:</p> +<div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">fmt</span><span class="o">::</span><span class="n">format</span><span class="p">(</span><span class="s">"{0}, {1}, {2}"</span><span class="p">,</span><span class="w"> </span><span class="sc">'a'</span><span class="p">,</span><span class="w"> </span><span class="sc">'b'</span><span class="p">,</span><span class="w"> </span><span class="sc">'c'</span><span class="p">);</span> +<span class="c1">// Result: "a, b, c"</span> +<span class="n">fmt</span><span class="o">::</span><span class="n">format</span><span class="p">(</span><span class="s">"{}, {}, {}"</span><span class="p">,</span><span class="w"> </span><span class="sc">'a'</span><span class="p">,</span><span class="w"> </span><span class="sc">'b'</span><span class="p">,</span><span class="w"> </span><span class="sc">'c'</span><span class="p">);</span> +<span class="c1">// Result: "a, b, c"</span> +<span class="n">fmt</span><span class="o">::</span><span class="n">format</span><span class="p">(</span><span class="s">"{2}, {1}, {0}"</span><span class="p">,</span><span class="w"> </span><span class="sc">'a'</span><span class="p">,</span><span class="w"> </span><span class="sc">'b'</span><span class="p">,</span><span class="w"> </span><span class="sc">'c'</span><span class="p">);</span> +<span class="c1">// Result: "c, b, a"</span> +<span class="n">fmt</span><span class="o">::</span><span class="n">format</span><span class="p">(</span><span class="s">"{0}{1}{0}"</span><span class="p">,</span><span class="w"> </span><span class="s">"abra"</span><span class="p">,</span><span class="w"> </span><span class="s">"cad"</span><span class="p">);</span><span class="w"> </span><span class="c1">// arguments' indices can be repeated</span> +<span class="c1">// Result: "abracadabra"</span> +</pre></div> +</div> +<p>Aligning the text and specifying a width:</p> +<div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">fmt</span><span class="o">::</span><span class="n">format</span><span class="p">(</span><span class="s">"{:<30}"</span><span class="p">,</span><span class="w"> </span><span class="s">"left aligned"</span><span class="p">);</span> +<span class="c1">// Result: "left aligned "</span> +<span class="n">fmt</span><span class="o">::</span><span class="n">format</span><span class="p">(</span><span class="s">"{:>30}"</span><span class="p">,</span><span class="w"> </span><span class="s">"right aligned"</span><span class="p">);</span> +<span class="c1">// Result: " right aligned"</span> +<span class="n">fmt</span><span class="o">::</span><span class="n">format</span><span class="p">(</span><span class="s">"{:^30}"</span><span class="p">,</span><span class="w"> </span><span class="s">"centered"</span><span class="p">);</span> +<span class="c1">// Result: " centered "</span> +<span class="n">fmt</span><span class="o">::</span><span class="n">format</span><span class="p">(</span><span class="s">"{:*^30}"</span><span class="p">,</span><span class="w"> </span><span class="s">"centered"</span><span class="p">);</span><span class="w"> </span><span class="c1">// use '*' as a fill char</span> +<span class="c1">// Result: "***********centered***********"</span> +</pre></div> +</div> +<p>Dynamic width:</p> +<div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">fmt</span><span class="o">::</span><span class="n">format</span><span class="p">(</span><span class="s">"{:<{}}"</span><span class="p">,</span><span class="w"> </span><span class="s">"left aligned"</span><span class="p">,</span><span class="w"> </span><span class="mi">30</span><span class="p">);</span> +<span class="c1">// Result: "left aligned "</span> +</pre></div> +</div> +<p>Dynamic precision:</p> +<div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">fmt</span><span class="o">::</span><span class="n">format</span><span class="p">(</span><span class="s">"{:.{}f}"</span><span class="p">,</span><span class="w"> </span><span class="mf">3.14</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">);</span> +<span class="c1">// Result: "3.1"</span> +</pre></div> +</div> +<p>Replacing <code class="docutils literal notranslate"><span class="pre">%+f</span></code>, <code class="docutils literal notranslate"><span class="pre">%-f</span></code>, and <code class="docutils literal notranslate"><span class="pre">%</span> <span class="pre">f</span></code> and specifying a sign:</p> +<div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">fmt</span><span class="o">::</span><span class="n">format</span><span class="p">(</span><span class="s">"{:+f}; {:+f}"</span><span class="p">,</span><span class="w"> </span><span class="mf">3.14</span><span class="p">,</span><span class="w"> </span><span class="mf">-3.14</span><span class="p">);</span><span class="w"> </span><span class="c1">// show it always</span> +<span class="c1">// Result: "+3.140000; -3.140000"</span> +<span class="n">fmt</span><span class="o">::</span><span class="n">format</span><span class="p">(</span><span class="s">"{: f}; {: f}"</span><span class="p">,</span><span class="w"> </span><span class="mf">3.14</span><span class="p">,</span><span class="w"> </span><span class="mf">-3.14</span><span class="p">);</span><span class="w"> </span><span class="c1">// show a space for positive numbers</span> +<span class="c1">// Result: " 3.140000; -3.140000"</span> +<span class="n">fmt</span><span class="o">::</span><span class="n">format</span><span class="p">(</span><span class="s">"{:-f}; {:-f}"</span><span class="p">,</span><span class="w"> </span><span class="mf">3.14</span><span class="p">,</span><span class="w"> </span><span class="mf">-3.14</span><span class="p">);</span><span class="w"> </span><span class="c1">// show only the minus -- same as '{:f}; {:f}'</span> +<span class="c1">// Result: "3.140000; -3.140000"</span> +</pre></div> +</div> +<p>Replacing <code class="docutils literal notranslate"><span class="pre">%x</span></code> and <code class="docutils literal notranslate"><span class="pre">%o</span></code> and converting the value to different bases:</p> +<div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">fmt</span><span class="o">::</span><span class="n">format</span><span class="p">(</span><span class="s">"int: {0:d}; hex: {0:x}; oct: {0:o}; bin: {0:b}"</span><span class="p">,</span><span class="w"> </span><span class="mi">42</span><span class="p">);</span> +<span class="c1">// Result: "int: 42; hex: 2a; oct: 52; bin: 101010"</span> +<span class="c1">// with 0x or 0 or 0b as prefix:</span> +<span class="n">fmt</span><span class="o">::</span><span class="n">format</span><span class="p">(</span><span class="s">"int: {0:d}; hex: {0:#x}; oct: {0:#o}; bin: {0:#b}"</span><span class="p">,</span><span class="w"> </span><span class="mi">42</span><span class="p">);</span> +<span class="c1">// Result: "int: 42; hex: 0x2a; oct: 052; bin: 0b101010"</span> +</pre></div> +</div> +<p>Padded hex byte with prefix and always prints both hex characters:</p> +<div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">fmt</span><span class="o">::</span><span class="n">format</span><span class="p">(</span><span class="s">"{:#04x}"</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p">);</span> +<span class="c1">// Result: "0x00"</span> +</pre></div> +</div> +<p>Box drawing using Unicode fill:</p> +<div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">fmt</span><span class="o">::</span><span class="n">print</span><span class="p">(</span> +<span class="w"> </span><span class="s">"┌{0:─^{2}}┐</span><span class="se">\n</span><span class="s">"</span> +<span class="w"> </span><span class="s">"│{1: ^{2}}│</span><span class="se">\n</span><span class="s">"</span> +<span class="w"> </span><span class="s">"└{0:─^{2}}┘</span><span class="se">\n</span><span class="s">"</span><span class="p">,</span><span class="w"> </span><span class="s">""</span><span class="p">,</span><span class="w"> </span><span class="s">"Hello, world!"</span><span class="p">,</span><span class="w"> </span><span class="mi">20</span><span class="p">);</span> +</pre></div> +</div> +<p>prints:</p> +<div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span>┌────────────────────┐ +│ Hello, world! │ +└────────────────────┘ +</pre></div> +</div> +<p>Using type-specific formatting:</p> +<div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="cp">#include</span><span class="w"> </span><span class="cpf"><fmt/chrono.h></span> + +<span class="k">auto</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">tm</span><span class="p">();</span> +<span class="n">t</span><span class="p">.</span><span class="n">tm_year</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">2010</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1900</span><span class="p">;</span> +<span class="n">t</span><span class="p">.</span><span class="n">tm_mon</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">7</span><span class="p">;</span> +<span class="n">t</span><span class="p">.</span><span class="n">tm_mday</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">4</span><span class="p">;</span> +<span class="n">t</span><span class="p">.</span><span class="n">tm_hour</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">12</span><span class="p">;</span> +<span class="n">t</span><span class="p">.</span><span class="n">tm_min</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">15</span><span class="p">;</span> +<span class="n">t</span><span class="p">.</span><span class="n">tm_sec</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">58</span><span class="p">;</span> +<span class="n">fmt</span><span class="o">::</span><span class="n">print</span><span class="p">(</span><span class="s">"{:%Y-%m-%d %H:%M:%S}"</span><span class="p">,</span><span class="w"> </span><span class="n">t</span><span class="p">);</span> +<span class="c1">// Prints: 2010-08-04 12:15:58</span> +</pre></div> +</div> +<p>Using the comma as a thousands separator:</p> +<div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="cp">#include</span><span class="w"> </span><span class="cpf"><fmt/format.h></span> + +<span class="k">auto</span><span class="w"> </span><span class="n">s</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">format</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">locale</span><span class="p">(</span><span class="s">"en_US.UTF-8"</span><span class="p">),</span><span class="w"> </span><span class="s">"{:L}"</span><span class="p">,</span><span class="w"> </span><span class="mi">1234567890</span><span class="p">);</span> +<span class="c1">// s == "1,234,567,890"</span> +</pre></div> +</div> +</section> +</section> + + + </div> + </div> +</div> + + + + <div class="footer" role="contentinfo"> + © Copyright 2012-present, Victor Zverovich. + Created using <a href="http://sphinx-doc.org/">Sphinx</a> 3.3.0. + </div> + +<script src="_static/bootstrap.min.js"></script> + + </body> +</html> \ No newline at end of file